The JIMWLK evolution
[1]}, [2]}, [3]}, [4]}, [1]}, [2]},
or mainly its large \(N_c\) /mean field version, the Balitsky-Kovchegov (BK)
equation [7]}, [8]}, [9]},
have been instrumental for phenomenology of high energy QCD. So far,
most of the phenomenology have been done using the LO formulation. Yet, in order to
disentangle the gluon saturation effects it is critical to improve precision of the theoretical calculations
by going beyond the LO. A lot of progress has been achieved in this direction
over the last fifteen years or so. Particularly, NLO formulation of both the BK equation
[10]}
and JIMWLK Hamiltonian became available
[11]}, [12]}
starting the era of NLO phenomenology
[13]}, [14]}.
It was discovered that at NLO, there emerge conceptual problems related to
large energy independent new logarithmic corrections, threatening stability of the \(\alpha _s\)  expansion. A lot of efforts have been invested over the years attempting to fix these problems
[15]}, [16]}, [17]}, [18]}, [19]}, [20]}, [21]}, [22]}.
While overcoming them is critical in order to gain full control over the calculations and achieve
the desired NLO accuracy, these research directions are in a sense orthogonal to our goals
below and hence would not be reviewed in any detail here.
